Art of electrical precipitation of particles from fluid streams.



C. W. GIRVIN.

ART OF ELECTRICAL PRECIPITATION 0F PARTICLES FROM FLUID STREAMS.

APPLICATION FILED MAR- 22. 1917.

1,252,104. I Patented 'Jan. 1, 1918,.

2 SHEETS-SHEET l.

C. WLGIRVIN. ART OF ELECTRICAL PRECIPITATIDN 0F PARTICLES FROM FLUIDSTREAMS.

APPLICATION FILED MAR- 22. I911- Patented Jan. 1, 1918.

2 SHEETS-SHEET 2- l memom I WM) UNITED sT-Atr s PATENT OFFICE,-

CHABLESW. GIBVIN, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOB 0F ONE-TENTHT0 VALENTINE G. SCOTT, 0F PHILADELPHIA, PENNSYLVANIA, AND ONE-TENTH TOHORACE G. SEI'IZ, 01'! NEW YORK, N. Y.

ART OF ELECTRICAL PRECIPITATION OF PARTICLES-FROM FLUID STBE AMS.

Specification at Letters Patent. Patented Jan, 1, 1918.

Application filed March 22, 1917. Serial No. 156,565.

To all whom it may concern:

Be it knownthat I, CHARLES W. GIRVIN, acitizen of the United States,residing at Philadelphia, in the county of Philadelphla and State ofPennsylvania, have invented certain new and useful Improvements in theArt of Electrical Precipitation of Particles from Fluid Streams, ofwhich the following is a specification.

My present invention relates to the art of electrical precipitation ofparticles from fluid streams.

Practice of this art'involves the creation of anionization field orfields in the flow path of a stream and collection of the depositson thestream boundary or bounda connected to the source, the stream passing ain the direction of length of the pipe and through the field formedbetween the pipe and Wire. A preferred form of apparatus ings, certaindifiiculties appear.

stance, one of the inherent results of the preemploys the corona type ofdischarge in producing the field, although other types have also beenemployed;

In practising this art under prior teach- For incipitation by a field ofthis character is. that while deposits are collected on the streamboundary, such deposits will adhere thereto during activity of the fieldwith the result that the deposits build up and decrease the distancebetween the electrodes to a point where disruptive discharges must andare formed across the field, practically shortcircuiting the apparatuswhile the are remains; this renders it difiicult to operate the;

this-difficulty, the efficiency is reduced unless therate of liow of thestream be greatly reduced, thus materially decreasing the ca pacity ofthe apparatus. While such change may increase the time betweensuccessive dis ruptive discharges they are not thereby avoided.

It has been contemplated to meet this by employing the disruptivedischarge 'to dis lodge the deposits, but this necessarily involvcs'meetingv the problem of preventing damage to appara us by suchdischarges. Various other soluiions have been contemplated, but, so faras I am aware,'each advantage gained isat the sacrifice of some otheradvantageous feature, so thatthe combined result is approximately thesame high cleaning efiiciency with low capacity, or

the reverse. It is well known that a field of this type will produce thedeposits and clean the stream, but the principal problemis apparently toclean the cleaner. p

This problem of cleaning the cleaner is met in thepresent invention bynot attempting to provide any cleaning action in the active portion ofthe field, but produce the deposit collection within theactive portionof the field and shift the collecting surface into an inactive portionof the field Where the deposits are removed,v thus permittingsuch'building-up of collected deposits. but

removing the collecting surface before the building-up action hasreached a stage where the disruptive-discharge conditions are present.Obviously complete absence of disruptive discharge formations may noticeprovidedservice conditions may provide an excess of precipitateddeposits under abnormal conditions-but such discharge formatiolns becomethe exception instead of the ru e. v

' A preferred form of apparatus for carrying out the general principlesof the invention is to employ a rotatable collecting electrodewithastationary active electrode, the two electrodes being relativelyformed as to provide active and inactive portions of the ionization orelectric field. By mounting a deposit-removing device in such inactiveportion, the deposits collected in the active portion ofthe field arebrought to the re" moving device and the collecting electrode.

more or less cleaned. Obviously, the else trode may be movable indirections other than rotatable, and it is to be understood that theinvention contemplates the various ways in which the collectingelectrode may be shifted between active and inactive portions of thefield.

To these and other ends, therefore, the nature of which will be readilyunderstood as the invention is hereinafter disclosed, said inventionconsists in the improved methods of deposit precipitation and removaland the construction and combinatlon of parts for carrying such methods1nto etl'ect, as hereinafter more fully descr bed, illustrated in theaccompanying drawings, and more particularly pointed out in the appendedclaims. r

1n the accompanymg drawings, 1n which similar reference charactersindicate simllar parts in each of the V1BWS,-.

Figure 1 is a central vertical sectional view taken through an apparatusembodying the general principles of myinventlon, the structure formingone embodiment in which the general prmciples may be made serviceable.

Fig. 2 is a cross-sectional view w1th parts broken away.

Fig. 3 is a detail sectional view taken on line 33 of Fig. 2.

In the present embodiment, the field is shown as annular, and may beconsidered either as a single or a double field, dependent on whetherthe active electrode is in the form of a solid or skeleton structure. Ineither case the collecting electrode system is in the form of twoconcentrically arranged cylinders 10 and 11 between'which is located theactive electrode 12 which, in the form shown is in the form of a support12-solid or skeletonized as may be preferred--carry1ng a plurality ofedgeforming members 12 suitably spaced apart and extending in planeswhich intersect the axes of the cylinders. The drawings show the membersas extending in horizontal planes, but it is obvious that this may be'varied to a, more or less extent, as by having their directions oflength more or less in clined to the horizontal. Members 12 in the formshown, are preferably on opposite sides of the support, cooperating withthe opposing collecting electrode faces of cylinders 10 and 11.

As shown in Fig. 2, members 12 do not complete the circle although theelectrode is of a form concentric to cylinders 10 and 11. A gap is thusformed in the circle, which gap produces an inactive portion of thegeneral ionization field the active portion of which lies betweenmembers 12 and the opposing faces of the cylinders 10 and 11.

Electrode .12 is supported in suitable manner, as by a supporting member12" com nected to the electrode by a spider structure 12, a suitableportion of the electrode system being connected to a source of highpotential (not shown). It is to be understood, of course, that the partswill be suitably insulated.

The collecting electrode system (cylinders 10 and 11) is mounted on aturn-table structure 13 of suitable configuration and supported onrollers 14 properly located to permit a rotative movement to theturntable. Such movement may be provided in any suitable manner, as byconnecting one of the rollers to a rotatable shaft 15, the weight of theturntable'and the parts carried thereby tending to produce sufiicientfriction to drive the turntable. Obviously, other ways of rotating theturntable or cylinders may be employed.

As shown,.the turntable is arranged to close the interior .ofcylinder10- from the flowing stream, while that portion of the turntable leadingto the space between the cylinders may be more or less spider-like inform (Fig. 2) to permit the stream-entering from belowto pass into suchspace.

16 designates a casing within which the structure is located, the casinghaving an entrance 16'- and a discharge 16 Mounted in the inactive gapof the field is a suitable deposit-removing device. In the drawings th1sis shown as a scraper 17 which has its advance edges in contact with orin juxtaposition to the deposit-collecting faces of the cylinders. Thescraper may be of suitable cross-sectional contour, that shown beingsemi-circular within the inactive zone and forming a ready passage forthe removed deposits which drop to the bottom of the scraper on to asuitable trapdoor 17 which permits passage of the deposits into acollecting chamber 18 which is also preferably closed by a trap-door 18.

To prevent as far as possible direct entry of the stream into theinactive space or gap of the field, I preferably employ abaflie 17 atthe lower end of the scraper and a baflielike structure 17 at the top ofthe scraper, baflle 17 tending to direct the entering stream away fromthe position of the scraper, bafile 17 tending to force any portion ofthe stream contents which may have shifted toward the scraper away'fromthe space. In other Words, the two bafiies tend to close the oppositeends of the space immediately in front of the scraper portion so as totend to reduce the flow or velocity of any stream contents therein, thustending to decrease the quantity of such contents which would passthrough the inactive portion of the field.

As will be understood scraper l7 is more or less illustrative. Otherforms of devices, as for instance, brushes, may be employed.

Members 12 each act as an active sleep efficiency and incidentallypermitting introde, thus forming a plurality of ionization zones throughwhich the stream passes while traversing the apparatus. Hence, thestream is subjected to maximum ion1zat1on action and the particles 'ormolecules Will be carried on to the collecting electrodes 10 and 11 inthe usual manner. However, the collectin faces of the cylinders arerotatable so that uring rotation the active portions of the surfaceswill pass from the active portions of the field into the inactive portion formed by the ap in the active electrode. and in which t e strainlines are absent or materially less effective. The depositremovingdevice is reached and the relative movement between collecting surfacesand the device causes the deposits to be removed, the surfaces againentering the active field portion and receiving new deposits.

As will be understood, the active portion of the field remains constantalthough the collecting surfaces are shifted between the active andinactive portions of the field. Hence the stream flow may be constantwith the rate based on the capacity of the field to remove the depositsunder normal opera tion, the deposit-removal problem being practicallyeliminated. In addition, the potential may be maintained close to thecritical break-down voltage, thus increasing the crease in rate ofstream flow, it being understood that the speed of rotation of thecollecting electrodes may be controlled so as to practically insure thatthe amount of de posits will not reach a depth suificient to cause thedisruptive discharge action excepting possibly under abnormalconditions. And in meeting these conditions the fact that the surface isconstantly changing position within the active portion of the field, andthe presence of a plurality of ionization zones through which the streampasses, tends to prevent formation of built-up deposits of largemagnitude at isolated points. The scraper may be in actual contact withthe collecting surfaces, thus cleaning them more or less thoroughly.However, this is not essential since a slight spacing will be effective,the presence of a small deposit on the surfaces reentering the activeportion of the field oflering no material objection.

While I have shown but one field structure, it will be readilyunderstood that by the addition of another cylinder concentric withthose shown together with an additional active electrode within thespace thus formed, an additional field may be provided, the cylinderbeing mounted on the turntable and the active electrode connected in theactive electrode system. And such additions may be duplicated asdesired, thus meeting the problem of capacity, since each additionalfield increases the .amount of gas, etc., which may pass the structure.It will be understood of course, that each field would have itsindividual removal device.

It will be obvious that the apparatus will operate with current of anyof the wellknown types, as for instance, pulsating, oscillating, or thecontinuous current type, the question of the more or less adherence ofdeposits bein practically eliminated.

While I ave shown the gap of the active electrode as extending in avertical plane, it will be understood that this may be varied to meetoperating conditions, the deposit-removal device being arrangedaccordingly. For instance, it may be arranged more or less inclined tothe vertical, in which case a baffle may project from the rear of thescraper to direct the adjacent portion of the stream into an activeportion of the field.

The terms fluid used herein is intended to include streams of eitherliquid or gaseous .solid matter, such, for instance, as solid streams ofpowdered material.

While I have herein shown and described one embodiment for carrying outthe general principles of my invention, it will be readily understoodthat the exigencies of installation and use and the character of work tobe performed may require various changes and modifications in theconstruction and arrangement of parts, and I desire to be understood asreserving the right to make any and all such changes or modifications asmay be required or deemed desirable in so far as the same may fallwithin the spirit and scope of the broad invention disclosed, asexpressed in the accompanying claims.

Having thus described my invention, what I claim as new is:

1. In the art of electrical precipitation from flowing fluid streams andin which deposits are collected on a stream boundary, the method ofremoving such deposits which consists in establishing a' permanentlyinactive zone in the electric field, shifting-the deposit-laden boundaryto such zone, and removing the deposits from the boundary while thelatter is within the zone.

2. In the art of electrical precipitation from flowing fluid streams andin which deposits are collected on a stream boundary, the method ofremoving such deposits which consists in establishing a permanentlyinactive zone in the electric field, moving the deposit-laden boundarylaterally of the direction of stream flow into such zone, and removingthe deposits from the boundary while the latter is within the zone.

3. The method of collecting and removing particles or molecules from aflowing fluid stream, which consists in establishing deposit material ona stream boundar within an active portion of the field, shiftlng thedeposit-laden boundary between the active and inactive field portions,and removing the deposits from the boundary while in the inactiveportion.

4. In the art of electrical precipitation from fluid streams, opposingelectrode systerns adapted to produce an electric field havingpermanently-located active and inactive portions, means for moving thesystems relatively to each other to bring a depositcollccting face intoan inactive portion of the field, and means for removing deposits whilein such inactive portion.

5. In the art of electrical precipitation from fluid streams, 0 posingelectrode systems adapted to pro uce an electric field havingpermanentlydocated active and inactive portions, means for moving thecollecting electrode system between the active and inactive portions,and means for removing the deposits while in theinactive portion.

6. In the art of electrical precipitation from fluid streams, opposingelectrode systom adapted to produce an electric field havmgpermanently-located active and inactive portions, means for rotating thecollecting electrode system on its axis to shift a deposit-collectingface between such field port1ons, and means active within such inactiveportion for removing the deposits from the face.

7. In the art of electrical precipitation from fluid streams, arotatable tubular collecting electrode, an active electrode extendingconcentrically and formed to pro- 1 duce permanently-located active andinac tive portions of an electric field on a cross section on thecollecting electrode, and means within the inactive portion of the fieldand rendered active by electrode rotalZlOIl for removing the depositswithin such lnactlve portlon.

In testimony whereof I have aflixed my signature in the presence of twowitnesses. CHARLES W. GIRVIN. Witnesses:

-V. G. Soo'rr, FRANCIS D. MAHoNn.

It is hereby certified that in Letters Patent No. 1,252,104, grantedJanuary 1, 1918, upon the application of Charles W. Girvin, ofPhiladelphia, Pennsylvania, for an improvement in The Art of ElectricalPrecipitation of Particles from Fluid Strearns," an error appears in theprinted specification requiring correction as follows: Page 4, line 40,claim 7, for the word on read of; and that the said Letters Patentshould be read with this correction therein that the same may conform tothe record of the case in the Patent Office. 1

Signed and sealed this 12th day of February, A. 0., 1918.

.1. T. NEWTON,

L'omm-issimurr of Patents.

